The purpose of this investigation is to study the absorption, distribution, metabolic fate and pharmacoligic effects of local anesthetics when they are administered as inhaled aerosols. The reasons for studying local anesthetic aerosols are (a) the potential use of local anesthetic aerosols as bronchodilators, and (b) the well established use of local anesthetics to provide topical anesthesia of the tracheobronchial tree. A basic component of the proposed investigation is a comparison between local anesthetics of several different classes with respect to their fate and pulmonary effects when administered as inhaled aerosols. All studies will be performed in the cat. Specific objectives in intact animals are (1) to correlate blood and lung drug levels with effect on respiratory resistance, (2) to compare effects of different local anesthetics as bronchodilators, and (3) to compare drug effects after administration of comparable doses as aerosols or i.v. infusions. Pulmonary metabolism of local anesthetics will be studied in experiments with isolated perfused lung.